Absorption length for photon propagation in highly dense colloidal dispersions

The absorption length for photon propagation in highly concentrated colloid al dispersions calculated from temporal intensity profiles of 100 femto-sec ond pulses is much longer than the absorption length obtained from the meas urements of static light transmission in the pure continuous phase fluid. T he difference between these two values is explained on the basis of small i nterparticle spacing at high particle concentration and hence shorter paths traveled by photons through the absorbing medium relative to the total dif fusive path in the dispersion. The two values are in good agreement when th e absorption length is rescaled with the interparticle separation.